Growth Of Breast Carcinoma Research Articles

Expression of the ets-1 proto-oncogene in human breast carcinoma: differential expression with histological grading and growth pattern.

The proto-oncogene, ets-1, is a transcription factor known to control the expression of a number of genes and has been postulated to play a role in cell growth, differentiation and tumour invasion. We examined 137 cases of breast carcinoma by immunohistochemistry and compared the degree of Ets-1 expression among the different histological types of invasive carcinomas. Ets-1 was not expressed in the normal breast epithelium nor in noninvasive carcinomas. Among the 137 breast carcinoma cases, 104 (83.2%) showed positive staining for the Ets-1 protein. Histologically, invasive ductal carcinomas expressed immunopositivity with intense staining for Ets-1 in the tumour cells. Ets-1 expression correlated with Bloom-Richardson grading in invasive ductal carcinoma (p<0.01). However, there was no correlation between Ets-1 expression and lymph node metastasis, "t" classification or TNM staging. In situ hybridization confirmed the presence of Ets-1 mRNA in breast carcinomas. The expression of Ets-1 mRNA was detected in two of three different kinds of cultured human breast carcinoma cell lines and one of three human breast carcinoma tissues by the reverse transcription polymerase chain reaction method. These findings suggest that ets-1 is overexpressed in ductal cells of the breast that have undergone malignant conversion and that ets-1 is one of the factors associated with tumour growth and histological differentiation of breast carcinomas.

Hypercholesterolemia Impairs Angiogenesis in Patients With Breast Carcinoma and, Therefore, Lowers the Risk of Metastases

Our aim was to study the effect of hypercholesterolemia on angiogenesis induced by breast carcinoma. Of 51 patients with invasive ductal carcinoma, 28 had hypercholesterolemia and 23 had normocholesterolemia. The intratumoral microvessel density (MVD) was evaluated by using anti-CD31 antibody. The expression of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) on endothelial and tumor cells was examined and graded semiquantitatively. Patients with normocholesterolemia had a higher MVD (76.4 ± 8.2) than those with hypercholesterolemia (54.6 ± 5.1) (P < .01). The risks of recurrence and distant metastasis were higher in patients with normocholesterolemia than in patients with hypercholesterolemia (P < .01). Patients with hypercholesterolemia showed lower expression of endothelial VEGF and bFGF than patients with normocholesterolemia (P < .05 and P < .01, respectively). In addition, tumoral bFGF and VEGF expression showed negative correlation with the presence of hypercholesterolemia (P < .01). We suggest that hypercholesterolemia impairs angiogenesis by suppressing endothelial and tumoral bFGF and VEGF expression and, therefore, lowers the risk of metastases in cases of invasive breast carcinoma. Breast carcinoma is the most important malignant tumor among women, and it is a heterogeneous disease clinically and pathologically. It has been shown that tumor angiogenesis has an important role in the growth, invasion, metastasis, and recurrence of breast carcinoma. 1,2

Insulin-like growth factor (IGF)-system mRNA quantities in normal and tumor breast tissue of women with sporadic and familial breast cancer risk.

The insulin-like growth factor (IGF)-system plays a role in breast cancer susceptibility as well as in growth and progression of breast carcinomas. So far, findings have been based on serum IGF-I levels and semi-quantitative assessment of IGF-system expression levels in model systems and human tissue. Quantitative data on mRNA expression in different types of human breast tissue are lacking. Breast tissue samples ( n = 83) were available from 72 women. Messenger RNA expression of IGF-I, IGF-II, and their receptors (IGF-1R and IGF-2R) was assessed by real-time RT-PCR. We found a large variation in mRNA levels. Expression of each gene was significantly higher in normal tissue than in tumor tissue (median for normal and tumor tissue, respectively (arbitrary units); IGF-I: 25.2 and 1.4; IGF-II: 5.9 and 0.6; IGF-1R: 0.18 and 0.07; IGF-2R: 1.8 and 0.9; p < 0.0001, Mann-Whitney test). Interestingly, in tumor tissue from patients with a strong family history of breast cancer, expression of both receptors was higher than in sporadic patients (IGF-1R: 0.13 and 0.05, p = 0.04; IGF-2R: 1.1 and 0.8, p = 0.04). For cancer-free controls, expression of IGF-II and IGF-2R in normal breast tissue was also higher in women with a family history of breast cancer than in women without such a family history (IGF-II: 7.2 and 1.5, p = 0.02; IGF-2R: 2.6 and 1.5, p = 0.09). Our study quantitatively shows that mRNA expression levels of IGF-system components in the breast are generally higher in normal tissue compared with tumor tissue, and higher in tissue from women with a family history of breast cancer. A basis has therefore been created for studies aimed at understanding IGF as a breast cancer risk factor, the relationship between IGF-systems in serum and tissues, and effects of lifestyle factors on the IGF-system.

Prognostic Impact of Cyclooxygenase-2 in Breast Cancer

Cyclooxygenase (COX)—2, an inducible isoform of cyclooxygenases, regulates the rapid production of high levels of prostaglandins during inflammation. Cyclooxygenase-2 is overexpressed in a variety of malignant tumors. This review discusses epidemiologic and preclinical data on the role of COX-2 in the development and progression of breast cancer, and it will focus on recent studies that investigate the prognostic role of COX-2 in breast cancer. In rodent tumor models it has been shown that treatment with COX-1 or COX-2 inhibitors reduces incidence and growth of breast carcinomas. Possible mechanisms include regulation of invasion, increased proliferation, and suppression of apoptosis by COX-2. Moreover, there may be an indirect effect of prostaglandins, for example in tumor—host interactions such as induction of stromal aromatase activity or enhancement of angiogenesis in tumor tissue. At least 8 different immunohistochemical studies have investigated expression of COX-2 in a total of 2392 primary breast carcinomas, of which 40% were found to be COX- 2—positive. Overexpression of COX-2 is associated with indicators of poor prognosis, such as lymph node metastasis, poor differentiation, and large tumor size. Four studies have found that overexpression of COX-2 is linked to poor prognosis in breast cancer. These investigations provide the basis for further evaluation of a possible therapeutic effect of COX inhibitors in therapy of breast cancer.

Transcription factor Egr-1 supports FGF-dependent angiogenesis during neovascularization and tumor growth.

Current understanding of key transcription factors regulating angiogenesis is limited. Here we show that RNA-cleaving phosphodiester-linked DNA-based enzymes (DNAzymes), targeting a specific motif in the 5' untranslated region of early growth response (Egr-1) mRNA, inhibit Egr-1 protein expression, microvascular endothelial cell replication and migration, and microtubule network formation on basement membrane matrices. Egr-1 DNAzymes blocked angiogenesis in subcutaneous Matrigel plugs in mice, an observation that was independently confirmed by plug analysis in Egr-1-deficient animals, and inhibited MCF-7 human breast carcinoma growth in nude mice. Egr-1 DNAzymes suppressed tumor growth without influencing body weight, wound healing, blood coagulation or other hematological parameters. These agents inhibited endothelial expression of fibroblast growth factor (FGF)-2, a proangiogenic factor downstream of Egr-1, but not that of vascular endothelial growth factor (VEGF). Egr-1 DNAzymes also repressed neovascularization of rat cornea. Thus, microvascular endothelial cell growth, neovascularization, tumor angiogenesis and tumor growth are processes that are critically dependent on Egr-1.

A simple model of breast carcinoma growth may provide explanations for observations of apparently complex phenomena.

There has been great debate regarding the importance of ductal carcinoma in situ (DCIS) in the breast. Autopsy results that demonstrate a much greater number of these lesions compared with the number of invasive carcinomas, and the numbers of deaths from breast carcinoma each year have been cited as evidence that DCIS rarely leads to invasion and death. These analyses have overlooked the fact that, to sustain a rate of detection each year, there would have to be a reservoir of undetected breast carcinomas growing in the population. The authors developed a simple model that makes this clear. In addition, complex phenomena have been suggested to explain why invasive breast disease may grow more rapidly among very young women and more slowly among the very old. A simple model provides some insight that may simplify the explanation of these observations. The simple model of breast carcinoma growth assumes that there are three types of breast carcinoma that begin each year in a cohort of women. It assumes that all breast carcinomas begin as DCIS and take 9 years to go from a single cell to an invasive lesion for the slowest growing lesions, 6 years for intermediate growing DCIS lesions, and 3 years for fast-growing DCIS lesions. Furthermore, once an invasive clone forms, the model assumes that it will double in 60 days for fast-growing lesions, 120 days for intermediate growing lesions, and 180 days for slow-growing lesions. Three new tumors begin to grow in each successive year (one of each type). The model uses simple vectors that are defined by the size of the tumors and the time since tumor initiation, and it assumes that all tumors are detected when they reach 2 cm in greatest dimension. The model can be used to show graphically how many undetected tumors (DCIS as well as invasive carcinomas) there may be in the population to sustain the detection of three invasive tumors each year. Using the assumptions described above, the model showed that, by the time the first slow-growing breast carcinoma reaches 2 cm in greatest dimension, there will be 29 other slow-growing tumors that have not reached that size (9 DCIS and 20 smaller invasive carcinomas), 19 moderately growing tumors (6 DCIS and 13 smaller invasive carcinomas), and 9 fast-growing tumors (3 DCIS and 6 smaller invasive carcinomas). This means that, for every three breast tumors that reach 2 cm, the model predicted that there would be another 57 tumors (39 smaller invasive carcinomas and 18 DCIS) that would be undetected "below the surface". The model showed clearly that faster growing tumors would be expected to predominate among the youngest women, because they are the first to "reach the surface"; and, if the number of newly initiated tumors decreases with age, then there will be more of the slowest growing tumors that are left to reach the surface among the oldest women in the population. Even if the authors' assumptions are incorrect, their model made it clear that, to diagnose several breast carcinomas per 1000 women each year means that there have to be many more undetected carcinomas in the population to sustain the rate of detection. Although the model did not prove that DCIS may become potentially invasive and lethal, it did demonstrate that, even if all of these in situ lesions become invasive and lethal, many more DCIS lesions would have to be expected in the population than the number of invasive carcinomas detected each year and the number of deaths from breast carcinoma each year. Furthermore, the model provided a simple, purely mechanical illustration that may explain the preponderance of faster growing breast carcinomas among very young women and the preponderance of slower growing tumors among elderly women.

FGF-2-Interaktionen in Mammakarzinomen und gesundem Brustdrüsengewebe

Purpose: FGF-2 is a mitogen for many cell types. Stimulation of breast carcinoma cell proliferation by this growth factor has been reported. FGF-2 binding to its receptor tyrosine kinases (RTK) and cellular signaling are modulated by heparan sulfate proteoglycans (HSPGs). The role of these molecules in breast carcinoma growth control is unknown. HSPG alterations in breast carcinomas compared to normal mammary gland should be investigated. Material and Methods: 30 infiltrating breast carcinomas were examined. The ability of HSPGs to promote FGF-2 signaling complex assembly was tested. A FGF-2 ligand and a soluble RTK fusion protein (FR 1-AP) were used as binding probes. HSPG expression was measured by immunohistochemical detection of syndecan-1, syndecan-4 and glypican-1. Results: Other than normal gland epithelium, carcinoma cell HSPGs show increased FGF-2 binding. HSPG/FGF-2 complexes immobilize soluble FR 1-AP fusion protein, indicating that HSPGs promote FGF-2 signaling. Surprisingly, no single HSPG core protein co-localizes with this binding activity. Syndecan-1 is uniformly present in normal gland epithelium, but heterogeneously expressed in carcinomas. Syndecan-4 is highly expressed in normal gland epithelium, but reduced or lost in most carcinomas. It is lower in infiltrating than in in situ components, if both co-exist. No dramatic changes in glypican-1 expression are observed. Loss of syndecan-4 may convey an infiltrating, migratory phenotype to the carcinoma cells. Conclusion: The increased ability of carcinoma HSPG to promote FGF-2 signaling complex assembly is likely due to structural abnormalities of HS chains rather than altered core protein expression and may contribute to accelerated proliferation.

Ligands for the peroxisomal proliferator-activated receptor gamma and the retinoid X receptor inhibit aromatase cytochrome P450 (CYP19) expression mediated by promoter II in human breast adipose.

Local estrogen biosynthesis in breast adipose tissue, catalyzed by P450 aromatase, contributes to the growth of breast carcinomas. Aromatase expression is regulated by a number of alternative promoters, and in normal adipose tissue it is primarily regulated via the distal promoter I.4. However, in breast adipose containing a tumor, aromatase expression is regulated by the proximal promoter II in response to tumor-derived factors. Previously we have shown that peroxisomal proliferator-activated receptor gamma (PPARgamma) ligands inhibit aromatase expression in normal breast adipose tissue mediated by promoter I.4. In the present study, we investigated the effects of the PPARgamma ligand troglitazone and the retinoid X receptor (RXR) ligand LG101305 on aromatase expression mediated by promoter II. In cultured human breast adipose stromal cells, troglitazone or LG101305 alone inhibited aromatase activity and expression stimulated by inducers of promoter II, in a concentration-dependent manner, and this inhibition was greater in the presence of both ligands. Reporter gene assays showed that troglitazone and LG101305 inhibit transcription from promoter II of the CYP19 gene. However, EMSAs showed that PPARgamma and RXRalpha do not bind to promoter II of the CYP19 gene, indicating that PPARgamma- and RXR-mediated inhibition of aromatase expression via promoter II occurs through an indirect mechanism of action. Because ligands for PPARgamma and RXR inhibit aromatase expression in healthy breast adipose (via promoter I.4), as well as expression induced by tumor-derived factors (via promoter II), such compounds could find utility in the treatment of estrogen-dependent breast cancers.

Ligands for the Peroxisomal Proliferator-Activated Receptor and the Retinoid X Receptor Inhibit Aromatase Cytochrome P450 (CYP19) Expression Mediated by Promoter II in Human Breast Adipose

Local estrogen biosynthesis in breast adipose tissue, catalyzed by P450 aromatase, contributes to the growth of breast carcinomas. Aromatase expression is regulated by a number of alternative promoters, and in normal adipose tissue it is primarily regulated via the distal promoter I.4. However, in breast adipose containing a tumor, aromatase expression is regulated by the proximal promoter II in response to tumor-derived factors. Previously we have shown that peroxisomal proliferator-activated receptor γ (PPARγ) ligands inhibit aromatase expression in normal breast adipose tissue mediated by promoter I.4. In the present study, we investigated the effects of the PPARγ ligand troglitazone and the retinoid X receptor (RXR) ligand LG101305 on aromatase expression mediated by promoter II. In cultured human breast adipose stromal cells, troglitazone or LG101305 alone inhibited aromatase activity and expression stimulated by inducers of promoter II, in a concentration-dependent manner, and this inhibition was greater in the presence of both ligands. Reporter gene assays showed that troglitazone and LG101305 inhibit transcription from promoter II of the CYP19 gene. However, EMSAs showed that PPARγ and RXRα do not bind to promoter II of the CYP19 gene, indicating that PPARγ- and RXR-mediated inhibition of aromatase expression via promoter II occurs through an indirect mechanism of action. Because ligands for PPARγ and RXR inhibit aromatase expression in healthy breast adipose (via promoter I.4), as well as expression induced by tumor-derived factors (via promoter II), such compounds could find utility in the treatment of estrogen-dependent breast cancers.

Inhibition of tumour cell growth by hyperforin, a novel anticancer drug from St. John's wort that acts by induction of apoptosis.

Hyperforin is a plant derived antibiotic from St. John's wort. Here we describe a novel activity of hyperforin, namely its ability to inhibit the growth of tumour cells by induction of apoptosis. Hyperforin inhibited the growth of various human and rat tumour cell lines in vivo, with IC(50) values between 3-15 microM. Treatment of tumour cells with hyperforin resulted in a dose-dependent generation of apoptotic oligonucleosomes, typical DNA-laddering and apoptosis-specific morphological changes. In MT-450 mammary carcinoma cells hyperforin increased the activity of caspase-9 and caspase-3, and hyperforin-mediated apoptosis was blocked by the broad-range caspase inhibitor zVAD.fmk. When added to MT-450 cells, hyperforin, but not paclitaxel, induced a rapid loss of the mitochondrial transmembrane potential Deltapsi(m), and subsequent morphological changes such as homogenization and vacuolization of mitochondria. Monitoring of Deltapsi(m) revealed that the hyperforin-mediated mitochondrial permeability transition can not be prevented by zVAD.fmk. This indicates that mitochondrial permeabilization is a cause rather than a consequence of caspase activation. Moreover, hyperforin was capable of releasing cytochrome c from isolated mitochondria. These findings suggest that hyperforin activates a mitochondria-mediated apoptosis pathway. In vivo, hyperforin inhibited the growth of autologous MT-450 breast carcinoma in immunocompetent Wistar rats to a similar extent as the cytotoxic drug paclitaxel, without any signs of acute toxicity. Owing to the combination of significant antitumour activity, low toxicity in vivo and natural abundance of the compound, hyperforin holds the promise of being an interesting novel antineoplastic agent that deserves further laboratory and in vivo exploration.

Inhibition of growth of MDA-MB-468 estrogen-independent human breast carcinoma by bombesin/gastrin-releasing peptide antagonists RC-3095 and RC-3940-II

The growth of breast carcinoma is promoted by autocrine growth factors such as the bombesin (BN)-like peptides and epidermal growth factor (EGF). The stimulatory action of BN-like peptides can be blocked by the use of BN/gastrin-releasing peptide (GRP) antagonists. The authors investigated the effects of synthetic BN/GRP antagonists RC-3095 and RC-3940-II on tumor growth and the expression of mRNA for EGF receptors and three BN receptor subtypes in MDA-MB-468 human breast carcinoma. Athymic nude mice with xenografts of MDA-MB-468 human breast carcinoma were injected subcutaneously for 6 weeks with RC-3940-II at doses of 20 or 40 microg/day. In another study, the effects of RC-3940-II and RC-3095 were compared. RC-3940-II caused a significant and dose-dependent growth inhibition of MDA-MB-468 tumors in nude mice; therapy with either dose of RC-3940-II significantly (P<0.01) reduced the mean final tumor volume and weight compared with controls. RC-3940-II induced a persistent regression of > 50% of all tumors. One of 3 tumors treated with 20 microg of RC-3940-II and 3 of 5 tumors treated with 40 microg were found to have regressed completely by the end of the study. When RC-3940-II and RC-3095 were compared at the dose of 20 microg/day, both powerfully suppressed growth of MDA-MB-468 tumors, with RC-3940-II causing a complete regression of 2 tumors and RC-3095 a complete regression of 1 tumor. Receptor analyses of untreated MDA-MB-468 tumors revealed an overexpression of EGF receptors and two classes of binding sites for BN/GRP. mRNAs for receptors of GRP, neuromedin B, and BN receptor subtype-3 were detected by reverse transcriptase-polymerase chain reaction. A virtual arrest of growth or regression of MDA-MB-468 human breast carcinoma after therapy with RC-3940-II and RC-3095 indicates that these BN/GRP antagonists could provide a new treatment modality for breast tumors expressing BN and EGF receptors.

Annual Rhythm in the Growth of Human Breast Carcinomas as Reflected in the Histology of Their Growing Edge.

This histologic study of breast carcinoma, based on 100 consecutive cases, identifies a dynamic scenario at the tumor edge. Three main types of tumor edge were identified. An inactive edge, seen throughout the year, consisted of tumor cells lying in fibrous tissue that merged into the adjacent fatty tissue. An infiltrative edge was characterized by an acute microvascular response and the presence of fine lymph channels often containing embolic tumor cells. A capsular edge showed sharp tumor demarcation accompanied by proliferation and followed by lymphocyte infiltration. Infiltrative edges were found mainly in the first half of the year, and capsular edges in the second. Thus, the growth of individual breast carcinomas appears to be the result of a common series of growth phases at their advancing edge that follow an annual cycle. Int J Surg Pathol 8(1):39-47, 2000

NEWVSOLD FASHIONED OESTRADIOL ANTAGONISTS IN MAMMARY CARCINOMA: `IN VITRO' AND `IN VIVO' PHARMACOLOGICAL APPROACHES

The rationale underlying therapeutic strategies designed to inhibit the action of endogenous sex hormones in malignant breast cells is provided by the demonstration of their involvement in supporting the development and growth of breast carcinoma. The surgical removal of steroid-secreting glands, in order to reduce the level of oestrogens reaching their target tissues, has for years been substituted by the so-called endocrinotherapeutic approach, which is based on the counteraction of the steroid hormone activity by the hormonal receptor blockade with suitable antioestrogenic compounds. Over the past 25 years, the non-steroidal oestrogen antagonist tamoxifen has become the standard endocrine treatment for breast cancer. The triphenylethylene-derivative compound competes efficiently for binding to the oestrogen receptor, but the complex retains some transcriptional activity. Consequently, tamoxifen exhibits, both `in vitroandin vivo', a range of biological activity from full oestrogen antagonism to partial agonism. There is also evidence suggesting that the agonist activity of this compound may ultimately stimulate breast tumour growth, thus causing some treatment failures. Moreover, the use of tamoxifen is limited by the possible onset of drug-resistance in many patients. Nevertheless, widely tested tamoxifen has proved to be very helpful for the development of new compounds to be used as long-term adjuvant therapy or as preventive agents. These novel oestrogen antagonists belong to two major classes: tamoxifen analogs and new pure steroidal-like antioestrogens. The search for and development of compounds devoid of tamoxifen cross-resistance, with a safer toxicity profile as well as the lack of oestrogenic effects, provide the bases to improve the current therapeutic applications of antioestrogens.

Inhibition of Human Breast Carcinoma Growth by a Soluble Recombinant Human CD40 Ligand

AbstractCD40 is present on B cells, monocytes, dendritic cells, and endothelial cells, as well as a variety of neoplastic cell types, including carcinomas. CD40 stimulation by an antibody has previously been demonstrated to induce activation-induced cell death in aggressive histology human B-cell lymphoma cell lines. Therefore, we wanted to assess the effects of a recombinant soluble human CD40 ligand (srhCD40L) on human breast carcinoma cell lines. Human breast carcinoma cell lines were examined for CD40 expression by flow cytometry. CD40 expression could be detected on several human breast cancer cell lines and this could be augmented with interferon-γ. The cell lines were then incubated with a srhCD40L to assess effects on in vitro growth. srhCD40L significantly inhibited the proliferation of the CD40+ human breast cancer cell lines. This inhibition could also be augmented with interferon-γ. Viability was also affected and this was shown to be due to increased apoptosis of the cell lines in response to the ligand. Treatment of tumor-bearing mice was then performed to assess the in vivo efficacy of the ligand. Treatment of tumor-bearing SCID mice with the ligand resulted in significant increases in survival. Thus, CD40 stimulation by its ligand directly inhibits human breast carcinoma cells in vitro and in vivo. These results suggest that srhCD40L may be of clinical use to inhibit human breast carcinoma growth.

Inhibition of Human Breast Carcinoma Growth by a Soluble Recombinant Human CD40 Ligand

CD40 is present on B cells, monocytes, dendritic cells, and endothelial cells, as well as a variety of neoplastic cell types, including carcinomas. CD40 stimulation by an antibody has previously been demonstrated to induce activation-induced cell death in aggressive histology human B-cell lymphoma cell lines. Therefore, we wanted to assess the effects of a recombinant soluble human CD40 ligand (srhCD40L) on human breast carcinoma cell lines. Human breast carcinoma cell lines were examined for CD40 expression by flow cytometry. CD40 expression could be detected on several human breast cancer cell lines and this could be augmented with interferon-γ. The cell lines were then incubated with a srhCD40L to assess effects on in vitro growth. srhCD40L significantly inhibited the proliferation of the CD40+ human breast cancer cell lines. This inhibition could also be augmented with interferon-γ. Viability was also affected and this was shown to be due to increased apoptosis of the cell lines in response to the ligand. Treatment of tumor-bearing mice was then performed to assess the in vivo efficacy of the ligand. Treatment of tumor-bearing SCID mice with the ligand resulted in significant increases in survival. Thus, CD40 stimulation by its ligand directly inhibits human breast carcinoma cells in vitro and in vivo. These results suggest that srhCD40L may be of clinical use to inhibit human breast carcinoma growth.

Human bone marrow-derived mitogenic stimulation selective for breast carcinoma and neuroblastoma cells.

In patients with neuroblastoma (NB) or breast carcinoma (BC), metastatic disease in the bone marrow (BM) is observed more frequently than at any other site, and a high incidence of BM metastases in these patients is associated with advanced disease and poor prognosis. These observations suggest the presence of BM micro-environmental elements that are favorable for NB and BC tumor cell growth. The influence of normal human BM cell-derived conditioned medium (CM) on clonogenic growth of BC and NB cell lines was investigated in vitro. The effects obtained were compared with those on tumor cells with a lower potential for BM metastasis. CM from unstimulated cultures of normal, healthy, low-density BM cells reproducibly and markedly augmented clonogenic growth of 3 BC and 3 NB cell lines. In contrast, growth of cell lines established from human tumors with differing metastatic propensity was unaffected by BM CM. Initial characterization, using crude BM CM, indicated that mitogenic activity (i) is mediated by peptides released by the non-adherent fraction of low-density BM cells and (ii) is not abolished by neutralizing antibodies against various cytokines known to be produced by BM cells and to regulate hematopoietic cell growth. Our observations suggest that certain specific peptides in the BM micro-environment may be responsible for the preferential growth of NB and BC metastases in BM.

Immunohistologic Analysis of Estrogen Receptor Expression in Breast Carcinoma Precursor Lesions

: The growth of invasive breast carcinoma is facilitated by abnormal expression of estrogen receptor (ER), however, the status of ER during disease histogenesis is poorly defined. The extent of ER immunostaining (expressed as percentage of positive cells) was semiquantitated in the invasive (ICA) and corresponding in situ (CIS) components of 50 formalin-fixed, paraffin-embedded breast carcinomas and then compared to staining in normal terminal duct lobular units (TDLU) or hyperplastic lesions (if present) in the same tissue sections. Morphologically normal TDLUs from most cases (61%) exhibited ER staining in 11–30% of epithelial cells; only 10% of the cases had TDLUs demonstrating immunoreactivity in more than 50% of cells. In contrast, 80% of the hyperplastic lesions showed ER staining in more than 30% of epithelial cells, with 44% demonstrating immuoreactivity in more than 50% of epithelial cell nuclei (p = 0.01, chi-square test). Although most in situ carcinomas showed even more extensive ER staining than hyperplasias (>70% of cells were positive in 50% of cases), a significant subset (28%) of CIS exhibited staining in less than 10% of cells (p = 0.002, chi-square test). Invasive carcinomas were less often extensively immunoreactive (i.e., >50% of cells positive) than CIS (32% versus 58% for CIS) and there were five cases (10%) in which the CIS component was ER positive but the invasive component was ER negative. Finally, ER-positive carcinomas were significantly more often accompained by extensive CIS and/or proliferative breast disease (p = 0.007 and 0.003, respectively). The divergent levels of ER expression observed between premalignant, preinvasive, and invasive lesions suggests that inappropriate regulation of hormone receptors may be a factor that promotes early growth or progression in breast neoplasia, and ER-positive breast carcinomas are characterized by a different, possibly lengthier, histogenesis than ER-negative malignancies with a greater frequency of background hyperplastic lesions and a larger preinvasive component.

Steroidal and nonsteroidal oestrogen antagonists in breast cancer: basic and clinical appraisal.

Endogenous sex hormones, such as oestrogens, control the development and growth of breast carcinoma. Blocking the binding between the steroid hormone and its receptor using anti-oestrogenic compounds is one of the possible ways of impeding the action of oestrogens at the level of their target tissues. The nonsteroidal, triphenylethylenic, anti-oestrogen tamoxifen has so far been the standard compound for endocrine treatment of breast cancer. Nevertheless, it forms a complex with the oestrogen receptor which gives rise to a range of biopharmacological events, ranging from full oestrogen antagonism to partial agonism. Moreover, its use is limited by the possible onset of drug resistance in many patients. In spite of these restrictions, tamoxifen has proved to be very helpful as a starting point for the development of new, more efficacious compounds. In this article, Roberto Favoni and Alessandra de Cupis review and discuss tamoxifen, several of its derivatives and the steroidal-like anti-oestrogens in terms of laboratory development, pharmacology and clinical evaluation.

The role of stroma in breast carcinoma growth in vivo.

The malignant progression of tumors is thought to be related to the expression of oncogenes and loss of expression of tumor suppressor gene. These factors are intrinsic to the cancer cells themselves. However, carcinomas are also infiltrated by host cells (fibroblasts, endothelial cells, inflammatory cells) and surrounded by an extracellular matrix which is extensively remodeled. The extracellular matrix components and infiltrating host cells provide a microenvironment that conditions both tumor progression and the metastatic process. Transplantation of human tumors into athymic nude mice has become an important experimental approach to study the biology of human cancers. The different models developed so far are beginning to elucidate the role of matrix molecules, growth factors and enzymes as well as fibroblasts in tumor progression. These animal models are likely to provide a useful tool to evaluate new antitumor treatments.

Parathyroid hormone-related protein and hypercalcemia.

The discovery of parathyroid hormone-related protein (PTH-rP) arose from interest in the mechanisms by which certain cancers cause hypercalcemia without necessarily metastasizing to bone. The humoral hypercalcemia of malignancy (HHM) had for a long time been ascribed to inappropriate production of parathyroid hormone (PTH) by cancers. The amino-terminal portions of PTH-rP and PTH have essentially identical actions through a common receptor for PTH/PTH-rP: to elevate plasma calcium by promoting bone resorption and decreasing calcium excretion. Assays for plasma PTH-rP fail to detect protein convincingly in normal plasma, but measurable levels have been found in up to 100% of patients with HHM, in 75% of patients with breast carcinoma metastatic to bone, and in some hypercalcemic patients with miscellaneous cancers. Whereas PTH-rP clearly functions as a hormone in those cancers in which it is produced in excess, in normal circumstances it is produced locally in many tissues in which it is a paracrine effector. There appears to be little doubt that PTH-rP is the major mediator of hypercalcemia in patients with HHM, although it is possible that other factors (e.g., bone resorbing cytokines) also could contribute in some patients. In the case of breast carcinoma, another possible role arises for PTH-rP. The high incidence of PTH-rP production by primary breast carcinomas, elevated plasma levels in 60% of those with hypercalcemia and lytic metastases, and higher incidence of PTH-rP production in skeletal versus those with nonskeletal metastases have led to the hypothesis that PTH-rP might contribute to breast carcinoma growth in bone. Experimental evidence currently is available to support this hypothesis. The discovery of PTH-rP has contributed greatly to current understanding of the skeletal complications of cancer.